Melting Slant

[A3k]

Hey all,
I made some slants for the first time following the instructions on this link http://www.unm.edu/~draper/beer/slantuse.html . They looked like they were working when I put them in the fridge and they got hard, however when I took them out, put the yeast on the surface and got it warmer, the slants melted.

The medium of the slant was gelatine and wort (about 1040 SG)

Should I do the same but buy some actual Agar, the article I read said it didnt matter, but maybe it does.

Any help would be appreciated,

Cheers,
Al

 

[trevc]

Am I the only one that thinks these slants sound like tasty treats? Gummi-beers... mmmm.

 

[braufrau]

Agar melts at a higher T than gelatine, which is one reason it is preferred.

 

[Benniee]

I've made slants using gelatin and haven't had this problem. How much gelatin did you add?

The only time I've noticed something similar is when I was holding a slant in my hand in an attempt to get a little warmth in it - and the slant surface got a little "wobbly". Once the temp came back down again it went back to normal.

I don't think Agar has this problem as it "sets" at a higher temp.

Benniee

 

[Sprungmonkey]

either use more gelatin or use agar. I use about 15g/L of agar-agar.

 

[A3k]

Gee that was a lot of quick responses. Cheers.

This is what I added
250ml water
15g DME
20g Gelatine

If the Gelatine gets too hot, does it ruin it?

Also, I did have my test tube holder on a heat pad to try and get them to about 25 degrees. This probably didnt help at all. What temperature does everyone grow the yeast at?

I reakon Ill get some Agar tonight. Sounds like it should work

Cheers again
Al

 

[Thirsty Boy]

Yeah, the first batch of slants i made were on gelatine - they were quite melty. I had to re-do them with a lot more gelatine, then they were still melty, but not so much I couldn't use them.

I put them in the fridge so they hardened up a bit, then streaked them, the left them tilted over on their slant angle while the yeast did a bit of growing. Once the yeast had obviously taken - I put em back in the fridge still on the angle and only stood them up straight after they had firmed up again.

The next batch I made was with agar and they are perfect at room temp - go agar

 

[~MikE]

not sure if anyone has this problem when using gelatine but if the yeast secretes proteases then it will liquefy the media. use agar-agar, should be able to get it from an Asian supplies store of some sort. also it sets at 45C IIRC but melts/re-melts at a much much higher temperature. use at 20g/litre.

also, don't forget about the yeast slant register!

 

[A3k]

hehe, not sure what this means, but all comments are pointing to agar-agar.

if the yeast secretes proteases then it will liquefy the media.

use agar-agar, should be able to get it from an Asian supplies store of some sort. also it sets at 45C IIRC but melts/re-melts at a much much higher temperature. use at 20g/litre.

Lucky for me theres asian grocery store on my street, so can get some tonight.

The register sounds like a good idea, but i reckon i'll make sure that i get the slant working first.

Cheers

 

[Sprungmonkey]

looks like agar agar is the way to go - i use a lab quality agar from Merck. 15g/L - have never had an issue with melting at room temp.

 

[A3k]

Well after I noticed the melted slant, I took it off the heat pad. When I got back from work they were all solid again (sounds obvious hey), and there was yeast on the surface of most of them. Looks like these may be alright afterall.

I still went and got agar-agar as it sounds better. $150 for 25g, so thats not too bad. I got two and think I could just make up heaps of the slats and store them in the fridge for when Im ready to inoculate them.

Cheers for the help.

 

[A3k]

Wow, $150 for 25g is pretty expensive... $1.50

 

[~MikE]

looks like agar agar is the way to go - i use a lab quality agar from Merck. 15g/L - have never had an issue with melting at room temp.

do you go out of your way to buy it or do you conveniently have access to it? cos the only difference is the nutrient value. bacteriological agar is very low nutrient so as to accurately control what microbe-consumables go into the media. completely pointless for homebrew slanting purposes IMO.

 

[Sprungmonkey]

do you go out of your way to buy it or do you conveniently have access to it? cos the only difference is the nutrient value. bacteriological agar is very low nutrient so as to accurately control what microbe-consumables go into the media. completely pointless for homebrew slanting purposes IMO.

Work in a micro lab and have access to agar agar as well as an autoclave. Fairly convenient to be able to brew while working. Unfortunately I am only there for another 2 wks and then i start a new job... luckly in a brewery...

 

[~MikE]

Work in a micro lab and have access to agar agar as well as an autoclave. Fairly convenient to be able to brew while working. Unfortunately I am only there for another 2 wks and then i start a new job... luckly in a brewery...

niice. i wouldn't be surprised if the brewery had a micro lab setup of some sort, could be in luck